San Diego State University

Department of Civil, Construction, and Environmental Engineering

ENVE 441 – Water Treatment Engineering

Fall 2018

Due on Friday, December 7, 2018 at 1:00 p.m.

A new community near Rancho San Diego in San Diego County requires a water

treatment plant (WTP) that meets current regulations. You have been assigned to design the

basic water treatment processes for a 4 mgd conventional WTP with ozone (rapid mix,

coagulation, sedimentation, rapid sand filter, and ozone/chlorine disinfection). The peak flow

to average flow ratio is 1.5:1 for purposes of determining the number of treatment trains. The

WTP uses Sweetwater Reservoir as its source water with characteristics listed on the next page.

Design temperature range 5oC to 30oC. The geology limits basin depth to 20 feet.

For this project, you will prepare a report on the design of the WTP processes. Include

any necessary design criteria, chemicals, and calculations to design and size the processes. This

is an independent research project; you are expected to review available reference information

and determine the appropriate formula for sizing the processes on an individual basis.

The report should conform to the following requirements:

1. The report must be written using Microsoft office or other word processing software.

2. The report should include one cover page, at least two pages of text (12 point font,

single spaced), a process schematic with chemical addition indicated, a plan view

showing treatment trains, meq/L table, meq/L liter bar chart, water quality table

(influent vs. MCL), a summary table with design criteria and process dimensions for

each process, chemical equations, at least one photo, at least one calculation page,

and one reference page. Minimum is 6 total pages.

3. Submit hardcopy and electronic copy (by email – of the report

by the due date and time.

Suggested Format:

 Introduction – Discuss the WTP type and capacity, determine the number of treatment trains, draw the process schematic with chemical addition locations indicated, draw a simple plan view with treatment trains. (text, schematic, plan view) (can be hand drawn)

 Water Quality – prepare the influent water quality table to calculate milliequivalent per liter, draw the milliequivalent per liter bar chart, calculate hardness; list regulatory requirements MCL versus actual influent water quality in a table and indicate whether each constituent complies (water quality table, meq/L bar chart, MCL table vs. influent)

 Process Descriptions – Briefly discuss the function of each process. What does it involve? How does it work? List Chemical Equations for chemicals added (text, chemical equations, photo)

 Design Criteria – List the criteria used to design and size each process (summary table)

 Size Process – Size each process (summary table/calculations)

 References – List your references (reference page)

Process Sizing Requirements:  Rapid Mix – Volume, Length, Width, Depth, G, mixer hp, chemicals required(use L=W=D)  Flocculation – Volume, Length, Width, Depth, Detention Time, Velocity, G, mixer hp  Sedimentation – Volume, Length, Width, Depth, Detention Time, Velocity, Overflow

Rate, Weir Length, Number of Weirs, Traveling Bridge or Chain-and-Flight  Rapid Sand Filter – Filtration Rate, Media Diameter, Bed Depth, Required Head, Length,

Width, Depth, Quantity of Backwash Water, Percentage Used for Backwash Water  Disinfection – Disinfection Contact Basin used for both Chlorine or Ozone with Residual

Chlorine. Determine Concentration, Contact Time, Length, Width, Depth (for governing criteria of chlorine or ozone)

The project will be evaluated on the basis of technical quality, accuracy of information, and readability. The project will be graded out of 100% and the breakdown is as follows:

1. Plant layout, introduction, readability, organization of the report, references – 25% 2. Process descriptions, chemistry, technical quality, accuracy of information – 25% 3. Design criteria, sizing, calculations – 50%

Conventional Water Treatment Plant with Ozone

Influent Water Characteristics (2017)* (from Sweetwater Reservoir), average values

Turbity 7.9 NTU

Color 43 units

Total Organic Carbon 11.5 ppm

Calcium 100 ppm

Magnesium 25.6 ppm

Sodium 160 ppm

Bicarbonate 200 ppm

Sulfate 177 ppm

Chloride 245 ppm

pH 7.9

Iron 152 ppb

Manganese 203 ppb

*For other parameters see “Sweetwater Reservoir” in handout from Lecture

OZONE and Cl2


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